1. Field of the Invention
The present invention relates to an image signal processing unit that carries out signal processing on image signals generated by an imaging device.
2. Description of the Related Art
There is a lowest amount of received light for an imaging device to generate pixel signal of a minimum signal strength. If a light amount from an object is under this amount, an optical image of the object cannot be captured well. In the prior art, a method has been known in which pixel signals generated by some pixels in an imaging device are summed and outputted as a summed pixel signal. By summing up pixel signals, the imaging device can capture an optical image of a dark object. However, when summing up some pixel signals, the summed-up pixel signal, generated by some pixels that receive reflected light of a bright object, saturates.
Further, it has been proposed to capture the optical image in long and short exposure times and to carry out some signal processing in order to display an image including dark and bright objects clearly. However, an imaging device designed for such special use is necessary It is still difficult for an ordinary imaging device to display an image including dark and bright objects clearly.